In some cases, such as when a new exceptional minor branch is created. The branch may not exist in the downstream repo. For example, during an exceptional minor release (e.g. FW 20.3.x and Components: 20.2.x).
This commit introduces a fallback mechanism to handle such scenarios. If the current branch is not found in the downstream repository, the script will now fall back to the last known branch from the build information. This ensures that the files can be updated properly.
PR Close#63678
Previously located in the `aio` directory, the commit moves the docs file into `adev` and also moves the `script` used to generated them from the `angular-cli` repo.
PR Close#55242
